Are you using it successfully with ARCH_JAVA payloads :? like java/meterpreter/reverse_tcp ? Maybe I'm forgetting something but I don't get it.

On the other hand, looks hard to deploy a new war with the current exploit, should work with the jsp payloads (which need a windows or linux platform), but I don't think the current exploit should work to deploy a java meterpreter. Maybe trying to abuse the tomcat's autodeploy feature could be useful to deploy a new WAR with this exploit.

Otherwise, would worth to detect the remote platform and try a native payload in case autodeploy isn't enabled.